Much like the Humvees that participated in last month's Head 2 Head, the Mercedes-Benz G63 AMG and G63 AMG 6x6 in the latest installment are some of the toughest off-road vehicles money can buy. And you'll need a lot of money to buy the 6X6 - at least $500,000. We're not sure why Mercedes-Benz decided to improve the Geländewagen's already fabled off-road prowess by adding another rear axle, but after watching host Jonny Lieberman put it through its paces off-road (and off the ground!), it a

Vehicle performance tests are serious business, with reputations made or broken by things like braking distance, top speed, and lateral g-forces. King of the metrics, though, is the 0-60 run, which for unknown reasons has become the benchmark for what truly makes a car a performance machine.